Stray currents cause damage to railway and surrounding infrastructure in electrified railway systems. Various railway products such as third rail insulators and rail fasteners are designed to possess high electrical insulation capability to ensure the path of electric power and return currents flow in the railway environment as designed. However, harsh environmental conditions, especially in old subway tunnels create the environment for these currents to stray away from their intended path, causing substantial corrosive damage. Thus, it would be desirable to enable monitoring of stray currents as they occur through electrical leakage paths such as on the surface of third rail insulators via a hand held non-contact device or a train mounted receiver. The same concept can be used on other potential leakage paths such as electrically insulating rail fixation plates and overhead catenary lines.
Many transit agencies use third rails to transmit traction power to train cars. Third rails are separated by insulators 10 from railroad ties and the underlying track structure. The insulators are placed roughly at every ten feet carrying the continuous third rails and they are made of fiber reinforced compression molded plastics or porcelain materials (FIG. 1). Debris build-up on insulator elements (FIG. 2), especially in tunnels cause stray currents to leak on outer surfaces of insulators which result in destruction of the insulator itself and/or lead to rapid degradation of track infrastructure and/or other infrastructure elements such as utility lines around the railway track. Stray current related damage causes service disruptions and creates unplanned maintenance events when the damage is contained within the track structure, but it can also lead to major problems if surrounding infrastructure such as utility lines are damaged.